Recording instrument



Filed May 21, 1943 FIG].

5 H J 6, 4 M G 1 I 2 5 n- 2 7 B M w J 3 V 6 3 F 0 F H 1 2 W ALFRED CKROBERTSON INVENTOR BY ATTORNEY Patented Sept. 12, 1944 RECORDING INSTRUMENT Alfred C. Robertson, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application May 21, 194:, Serial No. 487,920

2 Claims. (01. 234-70) which may go from a summer temperature on the airfield to many degrees below zero at high altitudes, the plastic composition in which the trace is made becomes harder at low temperatures and the stylus does not make-a uniform trace at the different temperatures.

I have lessened this difficulty by using, instead of a stylus having a uniform spring pressure,

one in which the pressure increases as the temperature decreases.

Reference will now be made to the accompanying drawing, the four figures of which illustrate four different embodiments of my invention.

In all of the figures the recording material is indicated at I. This may be a coating of a plastic composition containing a pigment upon a supporting sheet of glass, ti -Der or otherimaterial or it may be a sheet of plastic in the surface of which the stylus cuts a trace. In each figure, also, the cutting member or stylus proper is designated 2, and the support for the recording material, which moves, carrying the sheet I, in the direction indicated by the arrow, is designated 3.

The several figures illustrate different struc-.

tures by which the stylus is supported from the frame but each embodies a theme-responsive element acting to increase the pressure of the stylus as the temperature decreases. In every case the stylus is carried by a frame, the vibra-,

tion of which is transmitted to the stylus.

Figure 1 shows the simplest and preferred structure in which the stylus 2 is supported at the outer end of the bimetallic strip 4, the other end of which is rigidly secured to the frame member 5. The strip bends toward the recording plate I as the temperature decreases and thus presses the stylus more firmly toward the support 3.

It is to be understood that in all forms the stylu may form a groove in the plastic layer either by cutting or by displacement of material. In Figure 2, the stylus 2 is shown as supported at the end of a leaf spring 8, the other end of which is rigidly secured to the frame member 1, which has a rigid arm 8 overhanging the spring Ii. Attached to the under side of. the arm 8 is an end of a bowed bimetallic strip 9, the other end of which bears against spring 8, the pressure increasing with decrease in temperature.

In Figure 3, the stylus is also shown as carrice by a leaf spring 8', attached to frame I having an overhanging arm l. A slightly bowed resilient metal sheet II has one end lying in the slot II in arm 8' and the other end inslot I! in a projection ii on spring 8'. A volume expansion device ll issecured to the center of the sheet l0 and to the frame I. This expands with heat and contracts with cold, decreasing or increasing respectively the pressure of sheet ll upon spring 6' and hence upon the stylus.

In Figure 4, the stylus 2 is mounted on one end of am It, the other end of which is pivoted at ii to the frame I'I. Pivoted at it to arm I6 is a bowed bimetallic strip Is, the other end of which engages loosely in a slot 2| in the weight II which slides freely along arm IS. The bimetallic strip tends to bow outwardly with decrease in temperature moving the weight toward the outer end of arm I6 and thus increasing the pressure on stylus 2.

The details and purpose of the particular recording instruments are immaterial to the present invention. They may be any type for recording sound, temperature, speed, barometric pressure, electrical or magnetic variations or any other variable.

The above instructions are shown by way of example but many other equivalents could be devised utilizing the principles of my invention.

Having thus described my invention, what I claim is:

1. An apparatus for making a record by making a groove in a plastic layer comprising a stylus, a supporting frame, means for supporting a sheet of record material, and means for-supporting the stylus from the frame, said last named means including an element responsive to decrease in temperature to increase the pressure of the stylus toward the supporting means.

2. An apparatus for making a record in a layer of plastic material by means of a stylus and comprising a supporting means for the layer, a frame, a bar carried by the frame and ALFRED C. ROBERTSON. 

